Per NFL Network's Ian Rapoport, Packers head coach Mike McCarthy said Montgomery's injury is "nothing of a serious nature" after he left the game in the first half. According to Pro Football Talk's Charean Williams, Montgomery was taken to the locker room for evaluation with athletic trainer Kurt Fielding.
Montgomery has worn a number of hats in Green Bay's offense, serving as both a wide receiver and running back. In 2017 (eight games), he rushed for 273 yards and three touchdowns and caught 23 passes for 173 yards and a score.
With Jamaal Williams and Aaron Jones also available out of the backfield this season, Montgomery is likely to return to a diverse role.
"He's a multi-positional player," McCarthy said at this year's scouting combine, per Wes Hodkiewicz of Packers.com. "He's a running back, but he gives us great flexibility to use him so many different ways. That won't change."
He added: "[Montgomery] has had availability issues every year, but he's established himself as a multiple-position player. I think he's really gotten better in his natural run instinct. Obviously what he can do in and out of the backfield is at a high level."
Losing that versatility would obviously hurt the Packers, though the team has other playmakers, from Davante Adams and Randall Cobb to Jimmy Graham. If Montgomery is out of action, Williams and Jones would share the backfield work, while Cobb could see more use as well.